Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc b1808 short in passenger's airbag (to +b)

Subaru Legacy BN/BS (2015-2019) Service Manual / Airbag system (diagnostics) / Diagnostic chart with trouble code / Dtc b1808 short in passenger's airbag (to +b)

DIAGNOSIS START CONDITION:

Ignition voltage is 10 V to 16 V.

DTC DETECTING CONDITION:

Short circuit failure in power supply (shorted in main harness power supply, shorted in passenger’s airbag power supply, shorted in airbag CM internal circuit power supply)

CAUTION:

Before performing diagnosis, refer to “CAUTION” in “General Description”. General Description > CAUTION

NOTE:

Prior to starting work, prepare two AIRBAG RESISTORs (98299PA040).

WIRING DIAGRAM:

Airbag system Airbag System > WIRING DIAGRAM

STEP	CHECK	YES	NO
1.CHECK POOR CONTACT OF CONNECTORS. Check for poor contact of the connectors between the airbag control module and the passenger’s airbag module.	Is there poor contact-	Replace the airbag main harness.	Diagnostic Chart with Trouble Code > DTC B1808 SHORT IN PASSENGER'S AIRBAG (TO +B)
2.CHECK AIRBAG MAIN HARNESS (PASSENGER’S AIRBAG HARNESS) (SHORTED TO POWER SUPPLY). 1) Turn the ignition switch to OFF, disconnect the battery ground cable, and wait for 60 seconds or more. 2) Disconnect the connectors (AB7) and (AB2). 3) Disconnect the passenger’s airbag module connector (AB9). 4) Disconnect the connectors (AB6, AB17, AB18) from airbag control module. 5) Using a probe, measure the voltage between the connector (AB9) and chassis ground. General Description > PREPARATION TOOL CAUTION: When measuring the voltage, make sure that the probe is inserted from the back side (harness side) of the connector. Also, do not insert the probe forcibly. Connector & terminal (AB9) No. 1 (+) — Chassis ground (−): (AB9) No. 2 (+) — Chassis ground (−):	Is the voltage less than 1 V-	Diagnostic Chart with Trouble Code > DTC B1808 SHORT IN PASSENGER'S AIRBAG (TO +B)	Replace the airbag main harness along with body harness.
3.CHECK AIRBAG CONTROL MODULE. 1) Connect the connector other than passenger’s airbag module connector (AB9). 2) Using a probe, short the terminals No. 1 and No. 2 of connector (AB9). General Description > PREPARATION TOOL CAUTION: When shorting the terminals, make sure that the probe is inserted from the back side (harness side) of the connector. Also, do not insert the probe forcibly. Connector & terminal (AB9) No. 1 — (AB9) No. 2: 3) Connect the battery ground terminal and turn the ignition switch to ON. 4) Clear the memory. Clear Memory Mode 5) Perform the Inspection Mode. Inspection Mode 6) Read the DTC. (Current malfunction) Read Diagnostic Trouble Code (DTC)	Is DTC B1805 displayed-	Diagnostic Chart with Trouble Code > DTC B1808 SHORT IN PASSENGER'S AIRBAG (TO +B)	Replace the airbag control module. Airbag Control Module > REMOVAL
4.CHECK PASSENGER’S AIRBAG MODULE. 1) Turn the ignition switch to OFF, disconnect the battery ground cable, and wait for 60 seconds or more. 2) Connect the passenger’s airbag module connector (AB9). 3) Connect the battery ground terminal and turn the ignition switch to ON. 4) Clear the memory. Clear Memory Mode 5) Perform the Inspection Mode. Inspection Mode 6) Read the DTC. (Current malfunction) Read Diagnostic Trouble Code (DTC)	Is DTC B1808 displayed-	Replace the passenger’s airbag module. Passenger’s Airbag Module > REMOVAL	Diagnostic Chart with Trouble Code > DTC B1808 SHORT IN PASSENGER'S AIRBAG (TO +B)
5.CHECK FOR ANY OTHER DTC ON DISPLAY. Read the DTC. (Current malfunction) Read Diagnostic Trouble Code (DTC)	Is any other DTC displayed-	Check DTC using “List of Diagnostic Trouble Code (DTC)”. List of Diagnostic Trouble Code (DTC)	Finish the diagnosis.

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Other materials:

Inspection mode procedure
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